Semiconductor devices having electrically and optically conductive vias, and associated systems and methods

ABSTRACT

Semiconductor devices having one or more vias filled with a transparent and electrically conductive material are disclosed herein. In one embodiment, a semiconductor device includes a first semiconductor die stacked over a second semiconductor die. The first semiconductor die can include at least one via that is axially aligned with a corresponding via of the second semiconductor die. The vias of the first and second semiconductor dies can be filled with a transparent and electrically conductive material that both electrically and optically couples the first and second semiconductor dies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/852,339, filed Dec. 22, 2017, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present technology generally relates to semiconductor devices, andmore particularly relates to semiconductor devices having one or morevias with a transparent and electrically conductive material disposedtherein.

BACKGROUND

Microelectronic devices, such as memory devices, microprocessors, andlight emitting diodes, typically include one or more semiconductor diesmounted to a substrate and encased in a protective covering. Thesemiconductor dies include functional features, such as memory cells,processor circuits, interconnecting circuitry, etc. Semiconductor diemanufacturers are under increasing pressure to reduce the volumeoccupied by semiconductor dies and yet increase the capacity and/orspeed of the resulting encapsulated assemblies. To meet these demands,semiconductor die manufacturers often stack multiple semiconductor diesvertically on top of each other to increase the capacity or performanceof a microelectronic device within the limited volume on the circuitboard or other element to which the semiconductor dies are mounted. Insome semiconductor die stacks, the semiconductor dies are electricallyinterconnected using through silicon vias (TSVs). The TSVs enable thesemiconductor dies to be stacked close to each other such that adjacentsemiconductor dies are spaced apart from each other by only relativelysmall vertical distances. This enables higher data transfer rates and,since the dies are stacked vertically, the total footprint of the stackcorresponds to the footprint of the largest die in the stack.

One concern with microelectronic devices having stacked semiconductordies is that increasing the TSV count of each semiconductor die in thestack often requires increasing the size of the semiconductor dies.However, it is often desirable to increase the TSV count to, forexample, improve power delivery to the stacked dies and/or improve datatransfer between the dies. Accordingly, there remains a need in the artfor methods and systems for improving the density or number of TSVs in amicroelectronic device having stacked dies without increasing the sizeof the stacked dies.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present technology can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present technology.

FIG. 1A is a cross-sectional view, and FIG. 1B is an enlargedcross-sectional view, of a semiconductor device in accordance withembodiments of the present technology.

FIG. 2A is a cross-sectional view, and FIG. 2B is an enlargedcross-sectional view, of a semiconductor device in accordance withembodiments of the present technology.

FIG. 3 is a cross-sectional view of a semiconductor device in accordancewith another embodiment of the present technology.

FIG. 4 is a schematic view of a system that includes a semiconductordevice configured in accordance with embodiments of the presenttechnology.

DETAILED DESCRIPTION

Specific details of several embodiments of semiconductor devices havingoptically and electrically conductive vias are described below. A personskilled in the relevant art will recognize that suitable steps of themethods described herein can be performed at the wafer level or at thedie level. Therefore, depending upon the context in which it is used,the term “substrate” can refer to a wafer-level substrate or to asingulated, die-level substrate. Furthermore, unless the contextindicates otherwise, structures disclosed herein can be formed usingconventional semiconductor-manufacturing techniques. Materials can bedeposited, for example, using chemical vapor deposition, physical vapordeposition, atomic layer deposition, spin coating, and/or other suitabletechniques. Similarly, materials can be removed, for example, usingplasma etching, wet etching, chemical-mechanical planarization, or othersuitable techniques. A person skilled in the relevant art will alsounderstand that the technology may have additional embodiments, and thatthe technology may be practiced without several of the details of theembodiments described below with reference to FIGS. 1A-4.

In several of the embodiments described below, a semiconductor deviceincludes a first semiconductor die having a first optical component anda second semiconductor die having a second optical component. A viaextends at least between the first and second optical components and hasa transparent and electrically conductive material disposed therein. Insome embodiments, the first and second semiconductor dies areelectrically and optically coupled through the transparent andelectrically conductive material in the via. For example, the first andsecond optical components can be configured to receive and/or transmitoptical signals along the via between the first and second semiconductordies. At the same time, the via can be coupled to a power source, aground, or another source of electrical signals. Therefore, the presenttechnology can advantageously increase the signal density that a singlevia is capable of carrying by configuring the via to transmit bothelectrical and optical signals. Accordingly, the present technology canreduce the area of a semiconductor die that is occupied by, for example,through silicon vias (TSVs), or maintain the same area while improvingdata transfer, power delivery, and/or other characteristics of asemiconductor device incorporating the semiconductor die.

As used herein, the terms “vertical,” “lateral,” “upper,” and “lower”can refer to relative directions or positions of features in thesemiconductor devices in view of the orientation shown in the Figures.For example, “upper” or “uppermost” can refer to a feature positionedcloser to the top of a page than another feature. These terms, however,should be construed broadly to include semiconductor devices havingother orientations, such as inverted or inclined orientations wheretop/bottom, over/under, above/below, up/down, and left/right can beinterchanged depending on the orientation.

FIG. 1A is a cross-sectional view of a semiconductor device 100 havingoptically and electrically conductive vias configured in accordance withan embodiment of the present technology. The semiconductor device 100includes a first semiconductor die 102 a and a second semiconductor die102 b (collectively “semiconductor dies 102”) adjacent to the firstsemiconductor die 102 a. In the embodiment illustrated in FIG. 1A, thesemiconductor device 100 includes two semiconductor dies stacked“front-to-back” (e.g., an active side of the second semiconductor die102 b faces a backside of the first semiconductor die 102 a that isopposite an active side of the first semiconductor die 102 a). Inpractice the semiconductor device 100 can include a different number ofsemiconductor dies, such as three dies, four dies, eight dies, sixteendies, or more. For example, in another embodiment, the semiconductordevice 100 can include a third semiconductor die 102 c (shown in hiddenlines) above the first semiconductor die 102 a, and a fourthsemiconductor die 102 d (shown in hidden lines) below the secondsemiconductor die 102 b. Likewise, as described in further detail withreference to FIGS. 2A-3, the semiconductor dies 102 may have othersuitable orientations such as “front-to-front.”

Each of the semiconductor dies 102 includes integrated circuitry 103, asubstrate 104 (e.g., a silicon substrate), and a connection layer 106 ona surface of the substrate 104. The integrated circuitry 103 caninclude, for example, a memory circuit (e.g., a dynamic random memory(DRAM)), a controller circuit (e.g., a DRAM controller), a logiccircuit, and/or other circuits. In some embodiments, the semiconductordies 102 can be identical (e.g., memory dies manufactured to have thesame design and specifications), while in other embodiments thesemiconductor dies 102 can be different from each other (e.g., differenttypes of memory dies or a combination of controller, logic, memory,and/or other dies). In certain embodiments, the semiconductor device 100can include other structures and features such as a casing (e.g., athermally conductive casing) that encloses the semiconductor dies 102within an enclosure; an interposer, a printed circuit board, and/oranother substrate carrying the semiconductor dies 102; and/or anunderfill material deposited or otherwise formed around and/or betweenall or a portion of the semiconductor dies 102.

As further illustrated in the embodiment of FIG. 1A, each of thesemiconductor dies 102 includes vias 120 (e.g., through-substrate viasor through-silicon vias) extending through the connection layer 106 andthe substrate 104 from a first side 108 a to a second side 108 b of thesemiconductor dies 102. More particularly, FIG. 1B is an enlargedcross-sectional view of a portion of the semiconductor dies 102 showingan individual via 120 of the first semiconductor die 102 a and anindividual via 120 of the second semiconductor die 102 b in accordancewith an embodiment of the present technology. With reference to FIGS. 1Aand 1B, the vias 120 each have a sidewall 123 that defines a cavity oropening filled with an optically and electrically conductive material121 (“conductive material 121”). In some embodiments, the conductivematerial 121 is a transparent metal. In certain embodiments theconductive material 121 is a metal oxide such as, for example, indiumtin oxide. In the embodiment illustrated in FIGS. 1A and 1B, the vias120 are generally cylindrical, having a generally circularcross-sectional shape. However, in other embodiments, the vias 120 canhave any other suitable shape such as, for example, a rectangular,square, polygonal, and/or other cross-sectional shape. Likewise, thesemiconductor dies 102 can include a greater number of vias 120 than thetwo vias 120 illustrated in the embodiment shown in FIG. 1A. Forexample, the semiconductor dies 102 can each include one, three, four,or more than four vias.

As shown in FIGS. 1A and 1B, when the first semiconductor die 102 a ispositioned adjacent (e.g., stacked over) the second semiconductor die102 b, the vias 120 that extend through the first semiconductor die 102a can be aligned with (e.g., axially aligned with) corresponding vias120 of the second semiconductor die 102 b such that the conductivematerial 121 extends substantially continuously between thesemiconductor dies 102. That is, a lower end portion of the conductivematerial 121 in the vias 120 of the first semiconductor die 102 a cancontact (e.g., abut) an upper end portion of the conductive material 121in the corresponding vias 120 of the second semiconductor die 102 b.Accordingly, the vias 120 can provide a continuous optical andelectrical path between the semiconductor dies 102. In some embodiments,only a subset of the vias 120 of the semiconductor dies 102 may bealigned such that they create an optical and electrical path between thesemiconductor dies 102. In certain embodiments, the semiconductor device100 may include one or more interconnect structures between thesemiconductor dies 102. For example, interconnect structures (e.g.,bumps, pillars, etc.) can be disposed between the vias 120 of thesemiconductor dies 102 and configured to provide an optical andelectrical connection between the vias 120.

The vias 120 can be formed using well known processes in the art. Forexample, the vias 120 can be fabricated by forming holes in thesubstrate 104 and/or the connection layer 106 of the semiconductor dies102, filling the holes with the conductive material 121, and thenthinning the substrate 104 at the first side 108 a (e.g., a backside) toexpose the conductive material 121 through the backside of the substrate104. The process for forming the holes can include a photolithographicprocess followed by one or more wet and/or dry chemical etch processes.In other embodiments, the semiconductor dies 102 can first be positionedadjacent to each other (e.g., stacked), and the vias 120 can be formedthrough both of the semiconductor dies 102 at the same time (e.g., as asingle via through the stack).

Each of the semiconductor dies 102 can further include opticalcomponents 110 optically coupled to corresponding ones of the vias 120.In some embodiments, the optical components 110 can be opticaltransceivers configured to receive and transmit optical signals by wayof the vias 120, photodiodes configured to receive optical signals fromthe vias 120, light-emitting diodes (LEDs) or other light sourcesconfigured to transmit optical signals through the vias 120, or somecombination thereof. In certain embodiments, the optical components 110are optical transceivers that permit direct two-way signal transferbetween the semiconductor dies 102 along a single pair of adjacent(e.g., aligned) vias 120. In other embodiments, the optical components110 can include a combination of LEDs and photodiodes that allow forone-way communication between the semiconductor dies 102—and/or betweenexternal circuitry (e.g., external light sources)—along a single pair ofadjacent vias 120.

In the embodiment illustrated in FIGS. 1A and 1B, the optical components110 (i) are each formed in a recess 105 of the substrate 104 of one ofthe semiconductor dies 102 and (ii) have an annular shape such that theysurround or substantially surround a portion of the vias 120. Therecesses 105 can be formed, for example, by a suitable etching or otherprocess for removing a portion of the substrate 104 before formation ofthe connection layer 106. In other embodiments, all or a portion of theoptical components 110 can be formed on the surface of the substrate104. Moreover, the optical components 110 can have other shapes andconfigurations. For example, multiple optical components 110 mightsurround a corresponding via 120 (e.g., a photodiode and a LED), and/orthe optical components 110 may only partially surround (e.g., bepositioned adjacent to) the vias 120.

The optical components 110 can comprise gallium arsenide, a differentsemiconductor material, and/or another suitable material or combinationof materials. In some embodiments, the optical components 110 can beformed by first forming a layer of semiconductor material on the surfaceof the substrate 104 and/or in the recesses 105 of the semiconductordies 102 (e.g., using an epitaxial growth process), and then selectivelyremoving portions of the semiconductor material. For example, in certainembodiments, the holes for the vias 120 can be formed (e.g., etched)through the layer of semiconductor material.

In the embodiment illustrated in FIGS. 1A and 1B, the optical components110 are positioned off an optical axis of the vias 120. Therefore, eachof the semiconductor dies 102 can include optical elements 112configured to direct (e.g., route) optical signals from/to the opticalcomponents 110 to/from the vias 120. The optical elements 112 can bewaveguides, diffraction gratings, or other suitable structures wellknown in the art for optically coupling the optical components 110 tothe transparent conductive material 121 disposed in the vias 120. Asshown, the optical elements 112 can be positioned in the recesses 105 ofthe semiconductor dies 102 between the optical components 110 and theconductive material 121. In other embodiments, the optical elements 112can be positioned differently with respect to the optical components 110and the conductive material 121 (e.g., on the surface of the substrates104).

In some embodiments, each of the semiconductor dies 102 can further havean insulating layer 122 formed at least partially between the substrate104 and the conductive material 121, and/or between the connection layer106 and the conductive material 121. For example, the insulating layer122 can be formed between the substrate 104 of the semiconductor dies102 and the conductive material 121 to electrically insulate theconductive material 121 from the substrate 104 which can, for example,comprise silicon and/or another semiconductor material. In certainembodiments, as described in further detail below, the connection layer106 can include another insulating material positioned adjacent to theconductive material 121 such that the insulating layer 122 need notextend between the connection layer 106 and the conductive material 121.

In addition to insulating portions of the semiconductor dies 102 fromthe conductive material 121, in some embodiments, the insulating layer122 can be configured to facilitate the transmission of optical signalsthrough the vias 120. For example, the insulating layer 122 can have alower index of refraction than the conductive material 121 such that theinsulating layer 122 at least partially acts as an optical waveguide foroptical signals transmitted through the conductive material 121. In someembodiments, the insulating layer 122 comprises a nitride (e.g., siliconnitride), an oxide, or another suitable insulating material. In certainembodiments, the insulating layer 122 can be formed during the processor processes used to form the vias 120. For example, after forming holesin the substrate 104 and/or the connection layer 106 of thesemiconductor dies 102, an insulating material can be deposited in theholes to form the insulating layer 122 prior to deposition (e.g.,plating, sputter deposition, etc.) of the conductive material 121.

As illustrated in the embodiment of FIG. 1B, the connection layer 106 ofeach the semiconductor dies 102 includes one or more layers of adielectric material 135, a first conductive layer 132, and a secondconductive layer 134 (collectively “conductive layers 132, 134”). Thedielectric material 135 electrically isolates the conductive layers 132,134 from each other. The first conductive layer 132 electrically couplesthe conductive material 121 in the vias 120 to at least a portion of theintegrated circuitry 103 (FIG. 1A) of the semiconductor dies 102 (e.g.,to a first circuit of the integrated circuitry 103). The secondconductive layer 134 electrically couples the optical components 110 toat least a portion of the integrated circuitry 103 of the semiconductordies 102 (e.g., to a second circuit of the integrated circuitry 103).

In general, the connection layer 106 can be formed using a suitablemetallization process as is well known in the art. For example, themetallization process can be a suitable process for forming layers ofdielectric and conductive material on the substrates 104 of thesemiconductor dies 102. The conductive layers 132, 134 can be traces,vias, etc., and can be made from, for example, copper, nickel, solder(e.g., SnAg-based solder), conductor-filled epoxy, and/or otherelectrically conductive materials. For example, as shown in FIG. 1B, thesecond conductive layers 134 can include a layer or trace portion 134 aand a via or plug portion 134 b electrically coupling the trace portion134 a to one of the optical components 110. The dielectric material 135may be formed from, for example, parylene, polyimide, low temperaturechemical vapor deposition (CVD) materials—such astetraethylorthosilicate (TEOS), silicon nitride (Si₃Ni₄), silicon oxide(SiO₂)—and/or other suitable dielectric, non-conductive materials. Inembodiments where the insulating layer 122 does not extend between theconnection layer 106 and the conductive material 121, the dielectricmaterial 135 can have a lower index of refraction than the conductivematerial 121 such that the dielectric material 135 at least partiallyacts as an optical waveguide for optical signals transmitted through theconductive material 121.

In operation, the vias 120 enable both optical signal transfer andelectrical signal transfer (e.g., power delivery) between thesemiconductor dies 102. That is, the vias 120 can carry optical signals(e.g. light) produced by the optical components 110 and/or from externalcomponents (not shown in FIGS. 1A and 1B), as well as electrical signalsfrom a power source, a ground, or another source of electrical signals.It is expected that the vias 120 can carry optical signalssimultaneously or substantially simultaneously as electrical signalswithout a degradation of either signal. Thus, by utilizing the same viastructure for both optical and electrical signal transmission, thepresent technology can advantageously increase the signal density in asemiconductor device without increasing the number of communicationlines (e.g., TSVs) in the device.

FIG. 2A is a cross-sectional view of a semiconductor device 200 havingoptically and electrically conductive vias configured in accordance withanother embodiment of the present technology. This example morespecifically shows two semiconductor dies arranged in a “front-to-front”configuration. The semiconductor device 200 can include featuresgenerally similar to those of the semiconductor device 100 described indetail above. For example, in the embodiment illustrated in FIG. 2A, thesemiconductor device 200 includes a first semiconductor die 202 a and asecond semiconductor die 202 b (collectively “semiconductor dies 202”)adjacent to the first semiconductor die 202 a. As shown, thesemiconductor dies 202 can be arranged in a “front-to-front”configuration (e.g., such that an active side of the first semiconductordie 202 a faces an active side of the second semiconductor die 202 b.)Each of the semiconductor dies 202 includes integrated circuitry 203, asubstrate 204 (e.g., a silicon substrate), and a connection layer 206 ona surface of the substrate 204.

As further illustrated in the embodiment of FIG. 2A, the connectionlayer 206 of each semiconductor die 202 can have a first side 207proximate the substrate 204 and a second side 209 opposite the firstside 207. Each of the semiconductor dies 202 includes vias 220 extendingthrough the connection layer 206 from the first side 207 to the secondside 209. More particularly, FIG. 2B is an enlarged cross-sectional viewof a portion of the semiconductor device 200 showing an individual via220 of the first semiconductor die 202 a and an individual via 220 ofthe second semiconductor die 202 b in accordance with an embodiment ofthe present technology. With reference to FIGS. 2A and 2B, the vias 220each have a sidewall 223 that defines a cavity or opening filled with anoptically and electrically conductive material 221 (“conductive material221”) such as, for example, indium tin oxide. As shown, the vias 220 ofthe first semiconductor die 202 a are at least partially axially alignedwith corresponding vias 220 of the second semiconductor die 202 b suchthat the conductive material 221 extends substantially continuouslybetween the semiconductor dies 202. The vias 220 can be formed usingwell known processes in the art. For example, the vias 220 can be formedusing etching and deposition techniques as described above, or can beformed as part of the process for forming the connection layers 206(e.g., by a suitable masking and plating process, or other additiveprocess).

Each of the semiconductor dies 202 further includes optical components210 optically coupled to corresponding ones of the vias 220. The opticalcomponents 210 can be optical transceivers, receivers, and/ortransmitters that enable communication between the semiconductor dies202, and/or between the semiconductor dies 202 and external circuitry.In the embodiment illustrated in FIGS. 2A and 2B, the optical components210 can be axially aligned with corresponding ones of the vias 220.Accordingly, the semiconductor device 200 need not include waveguides,diffraction gratings, or other components for coupling the opticalcomponents 210 to the vias 220—rather, the optical components 210 arepositioned to directly receive and/or transmit optical signals from/tothe vias 220. More particularly, in some embodiments, a portion of theconductive material 221 (e.g., an end portion of the conductive material221 proximate the first side 207 of the connection layer 206) can abutor nearly abut a corresponding one of the optical components 210.

The connection layer 206 of each the semiconductor dies 202 can includea (i) a first conductive layer 232 that electrically couples theconductive material 221 in the via 220 to at least a first portion ofthe integrated circuitry 203 (FIG. 2A) of the semiconductor dies 202;(ii) a second conductive layer 234 that electrically couples the opticalcomponents 210 to at least a second portion of the integrated circuitry203 of the semiconductor dies 202; and (iii) a dielectric material 235that electrically isolates the first conductive layer 232 and the secondconductive layer 234 from each other. Moreover, in the embodimentillustrated in FIGS. 2A and 2B, the vias 220 do not extend through thesubstrate 204 of the semiconductor dies 202, so an insulating materialneed not be provided around the conductive material 221 in the vias 220.In some embodiments, the dielectric material 235 can be configured tofacilitate the transmission of optical signals through the vias 220 by,for example, having a lower index of refraction than the conductivematerial 221 such that the dielectric material 235 at least partiallyacts as an optical waveguide for optical signals transmitted through theconductive material 221.

FIG. 3 is a cross-sectional view illustrating a semiconductor device 300in accordance with another embodiment of the present technology. Thisexample more specifically shows a semiconductor device having more thantwo semiconductor dies arranged in more than one configuration. Forexample, in the embodiment illustrated in FIG. 3, the semiconductordevice 300 includes a die stack 340 mounted to a package substrate 350.The die stack 340 includes a first semiconductor die 302 a coupled tothe package substrate 350, a second semiconductor die 302 b coupled to(e.g., stacked over) the first semiconductor die 302 a, a thirdsemiconductor die 302 c coupled to the second semiconductor die 302 b,and a fourth semiconductor die 302 d coupled to the third semiconductordie 302 c (collectively “semiconductor dies 302 a-302 d”).

As shown, the first semiconductor die 302 a and the second semiconductordie 302 b can be arranged in a “back-to-front” configuration. The secondsemiconductor die 302 b and the third semiconductor die 302 c canlikewise be arranged in a “back-to-front” configuration. Accordingly, insome embodiments, the first semiconductor die 302 a, the secondsemiconductor die 302 b, and the third semiconductor die 302 c(collectively “semiconductor dies 302 a-302 c”) can have featuresgenerally similar to (e.g., the same as) the semiconductor dies 102illustrated in the embodiment shown in FIGS. 1A and 1B. For example,each of the semiconductor dies 302 a-302 c can include vias 320 aextending entirely therethrough, and the vias 320 a can have anoptically and electrically conductive material 321 (“conductive material321”) disposed therein. Each of the semiconductor dies 302 a-302 c canfurther include optical components 310 a optically coupled tocorresponding ones of the vias 320 a.

As further illustrated in the embodiment of FIG. 3, the thirdsemiconductor die 302 c and the fourth semiconductor die 302 d arearranged in a “front-to-front” configuration. Accordingly, in someembodiments, the fourth semiconductor die 302 d can have featuresgenerally similar to (e.g., the same as) the semiconductor dies 202illustrated in the embodiment shown in FIGS. 2A and 2B. For example, thefourth semiconductor die 302 d can include vias 320 b extending onlypartially therethrough (e.g., through a connection layer of the fourthsemiconductor die 302 d) and having the conductive material 321 disposedtherein. Moreover, the fourth semiconductor die 302 d includes opticalcomponents 310 b optically coupled to corresponding ones of the vias 320b.

As shown, the vias 320 a of the semiconductor dies 302 a-302 c can bealigned (e.g., axially aligned) with each other and with the vias 320 bof the fourth semiconductor die 302 d such that the conductive material321 in the vias extends substantially continuously through the die stack340 to electrically and optically couple the semiconductor dies 302a-302 d. Moreover, in some embodiments, the vias 320 a of the firstsemiconductor die 302 a can be electrically and/or optically coupled tothe package substrate 350. The package substrate 350 can include aredistribution layer, an interposer, a printed circuit board, adielectric spacer, another semiconductor die (e.g., a logic die), oranother suitable substrate. The package substrate 350 can furtherinclude electrical connectors 352 (e.g., solder balls, conductive bumps,conductive pillars, conductive epoxies, and/or other suitableelectrically conductive elements) electrically coupled to the packagesubstrate 350 and configured to electrically couple the semiconductordies 302 a-302 d to external devices or circuitry (not shown). Forexample, in certain embodiments, the vias 320 a and 320 b can beelectrically coupled to an external power source or a ground through thepackage substrate 350.

In some embodiments, the package substrate 350 can include components(e.g., fiber optic components, waveguides, etc.) for routing opticalsignals between the semiconductor dies 302 a-302 d and external devicesor circuitry. In certain embodiments, the package substrate 350 canadditionally or alternatively include one or more optical componentsoptically coupled to the conductive material 321 in the vias. Forexample, the package substrate 350 can include optical transceivers,photodiodes, and/or LEDs for transmitting and/or receiving opticalsignals to/from the semiconductor dies 302 a-302 d.

In other embodiments of the present technology, a semiconductor deviceincluding a die stack with more than two dies, and optically andelectrically conductive vias extending through the die stack, can beprovided using any of the front-to-back or front-to-front arrangementsdescribed herein with reference to FIGS. 1A-3, or any combinationsthereof. For example, a semiconductor device according to the presenttechnology can include multiple front-to-front pairs of semiconductordies stacked 4-high, 6-high, 8-high, etc., multiple front-to-back pairsof semiconductor dies stacked 4-high, 6-high, 8-high, etc., or any othercombination.

Any one of the semiconductor devices having the features described abovewith reference to FIGS. 1A-3 can be incorporated into any of a myriad oflarger and/or more complex systems, a representative example of which issystem 400 shown schematically in FIG. 4. The system 400 can include aprocessor 402, a memory 404 (e.g., SRAM, DRAM, flash, and/or othermemory devices), input/output devices 405, and/or other subsystems orcomponents 408. The semiconductor devices described above with referenceto FIGS. 1A-3 can be included in any of the elements shown in FIG. 4.The resulting system 400 can be configured to perform any of a widevariety of suitable computing, processing, storage, sensing, imaging,and/or other functions. Accordingly, representative examples of thesystem 400 include, without limitation, computers and/or other dataprocessors, such as desktop computers, laptop computers, Internetappliances, hand-held devices (e.g., palm-top computers, wearablecomputers, cellular or mobile phones, personal digital assistants, musicplayers, etc.), tablets, multi-processor systems, processor-based orprogrammable consumer electronics, network computers, and minicomputers.Additional representative examples of the system 400 include lights,cameras, vehicles, etc. With regard to these and other example, thesystem 400 can be housed in a single unit or distributed over multipleinterconnected units, e.g., through a communication network. Thecomponents of the system 400 can accordingly include local and/or remotememory storage devices and any of a wide variety of suitablecomputer-readable media.

From the foregoing, it will be appreciated that specific embodiments ofthe technology have been described herein for purposes of illustration,but that various modifications may be made without deviating from thedisclosure. Accordingly, the invention is not limited except as by theappended claims. Furthermore, certain aspects of the new technologydescribed in the context of particular embodiments may also be combinedor eliminated in other embodiments. Moreover, although advantagesassociated with certain embodiments of the new technology have beendescribed in the context of those embodiments, other embodiments mayalso exhibit such advantages and not all embodiments need necessarilyexhibit such advantages to fall within the scope of the technology.Accordingly, the disclosure and associated technology can encompassother embodiments not expressly shown or described herein.

We claim:
 1. A semiconductor device, comprising: a first semiconductordie; a second semiconductor die positioned adjacent to the firstsemiconductor die; a via extending at least partially through the firstand second semiconductor dies; and an optically and electricallyconductive material in the via, wherein the optically and electricallyconductive material (a) optically couples the first and secondsemiconductor dies and (b) electrically couples the first and secondsemiconductor dies.
 2. The semiconductor device of claim 1 wherein— thefirst semiconductor die includes a first optical component opticallycoupled to the optically and electrically conductive material; thesecond semiconductor die includes a second optical component opticallycoupled to the optically and electrically conductive material; and thefirst and second optical components are selected from the groupconsisting of an optical transceiver, a photodiode, and a light emittingdiode.
 3. The semiconductor device of claim 1 wherein— the first opticalcomponent is formed on a first surface of a semiconductor substrate ofthe first semiconductor die; the second optical component is formed on asecond surface of a semiconductor substrate of the second semiconductordie; and the first and second surfaces face the same direction.
 4. Thesemiconductor device of claim 1 wherein the via further includes aninsulating material disposed at least partially between the opticallyand electrically conductive material and a semiconductor material of thefirst and second semiconductor dies, and wherein the insulating materialhas a lower index of refraction than the optically and electricallyconductive material.
 5. The semiconductor device of claim 2 wherein— thevia extends entirely through a substrate of the first semiconductor die;the first optical component is positioned off an optical axis of thevia; and the second optical component is axially aligned with theoptical axis of the via.
 6. The semiconductor device of claim 5 whereinthe first optical component is optically coupled to the optically andelectrically conductive material by an optical component, and wherein anend portion of the via abuts the second optical component.
 7. Thesemiconductor device of claim 6 wherein the optical element is at leastone of a waveguide or a diffraction grating, and wherein the transparentand electrically conductive material is indium tin oxide.
 8. Asemiconductor die, comprising: a substrate having integrated circuitry;a via extending at least partially through the substrate; an opticallyand electrically conductive material in the via; and an opticalcomponent for receiving and/or transmitting optical signals, wherein theoptical component is (a) optically coupled to the optically andelectrically conductive material in the via and (b) electrically coupledto the integrated circuitry.
 9. The semiconductor die of claim 8 whereinthe optical component is an optical transceiver formed from asemiconductor material.
 10. The semiconductor die of claim 8 wherein thevia extends entirely through the substrate.
 11. The semiconductor die ofclaim 8 wherein the optical component is (a) positioned off an opticalaxis of the via and (b) optically coupled to the optically andelectrically conductive material by an optical element.
 12. Thesemiconductor die of claim 8 wherein the transparent and electricallyconductive material is indium tin oxide.
 13. The semiconductor die ofclaim 8 wherein the optical component is formed on a surface of thesubstrate.
 14. The semiconductor die of claim 8 wherein the opticalcomponent is formed at least partially in a recess of the substrate. 15.The semiconductor die of claim 8 wherein the via further includes aninsulating material disposed at least partially between the opticallyand electrically conductive material and the substrate.
 16. Thesemiconductor die of claim 11 wherein the optical element is selectedfrom the group consisting of a waveguide and a diffraction grating. 17.The semiconductor die of claim 15 wherein the insulating material has alower index of refraction than the transparent and electricallyconductive material.
 18. A method of forming a semiconductor device, themethod comprising: positioning a first semiconductor die adjacent to asecond semiconductor die to at least partially align a first via of thefirst semiconductor with a second via of the second semiconductor die;electrically coupling the first semiconductor die to the secondsemiconductor die via an optically and electrically conductive materialdisposed in the first and second vias; and optically coupling the firstsemiconductor die to the second semiconductor die via the optically andelectrically conductive material.
 19. The method of claim 18, furthercomprising: attaching the first semiconductor die to a packagesubstrate; electrically coupling the first and second semiconductor diesto the package substrate via the optically and electrically conductivematerial; and optically coupling the first and second semiconductor diesto the package substrate via the optically and electrically conductivematerial.
 20. The method of claim 18 wherein positioning the firstsemiconductor die adjacent to the second semiconductor die includesaxially aligning a first optical transceiver of the first semiconductordie with a second optical transceiver of the second semiconductor die.